Aortic Dissection Presenting as a STEMI

Audience This scenario was developed to educate emergency medicine residents on the presentation and management of a patient with a Stanford type A aortic dissection. Introduction Chest pain is one of the most common chief complaints seen in the emergency department with a deadly differential diagnosis list. A “can’t miss” diagnosis, aortic dissection occurs when an intimal tear creates a false lumen in the aorta, with a variably reported incidence of approximately 2.5–5 per 100,000 person-years.1 This amounts to an estimated 8,000–16,000 cases per year in the United States with a mortality likely underestimated due to prehospital death ranging from 20–40% within 24 hours and 30–50% at 5 years.2,3,4 There is a reported increase in mortality by 1% for every hour the diagnosis is delayed, and half of diagnoses are made greater than 24 hours after presentation.5 The symptoms can range from chest pain to back pain, abdominal pain or extremity pain, to syncope or isolated neurologic deficits, even to shock or cardiac arrest.6 Aortic dissection is most commonly categorized into two groups: Stanford type A, involving the ascending aorta, and Stanford type B, involving only the descending aorta, and are generally managed surgically vs. medically respectively based on this paradigm.7,8 Stanford type A can be complicated by severe aortic regurgitation, pericardial tamponade or coronary artery occlusion mimicking ST-segment elevation myocardial infarction (STEMI). These potentials make it important to switch from heuristic to analytical thinking when developing a differential diagnosis.9 A high index of suspicion with early recognition and management is critical in this catastrophic disease state, especially given the propensity for complications and a wide variety of presentations. Educational Objectives At the conclusion of the simulation session or during the debriefing session, learners will be able to: 1) Verbalize the anatomical differences and management of Stanford type A and type B aortic dissections, 2) Describe physical exam findings that may be found with ascending aortic dissections, 3) Describe the various clinical manifestations of the propagation of aortic dissections, 4) Discuss the management of aortic dissection, including treatment and disposition. Educational Methods This session was conducted using a simulation scenario with a high-fidelity manikin as the patient and confederate/actor in the nursing role, followed by a post-scenario debriefing session on the presentation, differential diagnosis, potential physical exam findings, and management of patients with aortic dissection. Debriefing methods may be left to the discretion of the educators, but the authors have utilized advocacy-inquiry techniques.10 This scenario may also be run as an oral board examination case. Research Methods The residents are provided an electronic survey at the completion of the debriefing session to anonymously rate different aspects of the simulation, as well as provide qualitative feedback on the scenario. This survey is specific to the local institution’s simulation center. Results Twenty learners completed a feedback form. This session received all 6 and 7 scores (consistently effective/very good and extremely effective/outstanding, respectively) other than one isolated 5 score. The lowest average score was 6.5 for, “Before the simulation, the instructor set the stage for an engaging learning experience,” and the highest average score was 6.84 for, “The instructor identified what I did well or poorly - and why.” Feedback from the residents was overwhelmingly positive (available upon request). All groups initially gave aspirin upon identification of the STEMI and several gave heparin. Debriefing topics included STEMI mimics, physical exam findings for aortic dissection, imaging and laboratory workup for aortic dissection, blood pressure and heart rate goals and pharmacologic management, uncomplicated STEMI management, and Type I versus Type II decision-making. Discussion This is an easily reproducible method for reviewing management of patients with aortic dissection. There are multiple potential presentations and complications of aortic dissections to further customize the experience for learners’ needs. While it was discussed during debriefing that heparin administration was unlikely to cause immediate cardiopulmonary arrest, this state was included to reflect downstream hemorrhagic complications that may occur in the setting of antiplatelet administration for acute aortic dissection. Facilitators may choose to omit the arrest at their discretion. Topics Medical simulation, emergency medicine, aortic dissection, ST-elevation myocardial infarction, cardiovascular emergencies, hypertensive emergencies, STEMI mimics, vascular surgery, cardiothoracic surgery.


Linked objectives and methods:
Aortic dissection is a critical, elusive and time-sensitive diagnosis in a patient presenting with chest pain. In this case, providers will review the following high-yield aspects of aortic dissections. Providers will learn features and anatomy of a Stanford type A dissection and contrast to a type B aortic dissection (Objective 1). This will include a review of historical and physical exam findings associated with aortic dissection (Objective 2), clinical manifestations and complications of aortic dissection propagation (Objective 3), and the management of aortic dissection (Objective 4). Objectives were tracked by facilitators taking notes during the simulation scenario for further discussion during debriefing. This simulation scenario allows learners to reinforce their aortic dissection diagnosis and management skills in a physically and psychologically-safe learning environment, and then receive formative feedback on their performance.

Recommended pre-reading for instructor:
The authors recommend instructors review literature regarding the consensus treatment for aortic dissection, including epidemiology, presenting signs/symptoms, diagnosis, and management. Suggested readings include materials listed below under the "References/suggestions for further reading" section.

Results and tips for successful implementation:
This simulation was written to be performed as a high-fidelity simulation scenario, but also may be used as a mock oral board case.
The case was written for emergency medicine residents. This aortic dissection simulation case was conducted for approximately 30 emergency medicine residents during December 2021. The residents found the initial steps of management challenging, as all residents provided antiplatelets and several ordered heparin upon receipt of the initial electrocardiogram.
To make the case easier, the patient may emphasize different symptoms, such as upper back pain, the classically-taught "tearing" chest pain, simultaneous chest and abdominal pain, or divulge use of cocaine or a family history of connective tissue disorders. The previous chest x-ray may also be shown unprompted after learners review the new chest x-ray's images.
An oral boards style-presentation may reveal the diagnosis earlier because a facilitator asking learners exactly what they are looking for in an organ system with a positive physical exam finding may reveal a murmur or asymmetrical pulses to palpation, regardless of the learner's intent.
The local institution's simulation center feedback form is based on the Center of Medical Simulation's Debriefing Assessment for Simulation in Healthcare (DASH) Student Version Short Form 11 with the inclusion of required qualitative feedback if an element was scored less than a 6 or 7. Twenty learners completed a feedback form. This session received all 6 and 7 scores (consistently effective/very good and extremely effective/outstanding, respectively) other than one isolated 5 score. The lowest average score was 6.5 for "Before the simulation, the instructor set the stage for an engaging learning experience," and the highest average score was 6.84 for "The

Case Description & Diagnosis (short synopsis):
Patient is a 50-year-old female who presents to an academic emergency department ("American Board of Emergency Medicine General") with chest pain. The confederate/actor in the nursing role will start the case by first presenting an electrocardiogram (ECG) to the learners, stating, "50-year-old female with chest pain came into triage. Here's her ECG. We just brought her back into a bed." If nursing is asked, they urgently brought her into a bed because "we didn't like how her ECG looked." Her chest pain is sharp, radiates to her back, began suddenly, and causes her difficulty in breathing, but she will not divulge radiation to the back unless specifically asked. The patient is diaphoretic with discrepant radial pulses to palpation and an aortic regurgitation murmur. If the manikin is unable to demonstrate these physical exam changes, they can be verbalized by the nurse or by the facilitator if learners specifically ask if these findings are present, or if they simultaneously check bilateral radial pulses. If bilateral upper extremity blood pressures are obtained, there is a difference greater than 20 mmHg between both arms. Laboratory findings demonstrate an elevated troponin, an elevated d-dimer, and a chest x-ray (CXR) with a widened mediastinum.
Hypertension and tachycardia will worsen at minute 6 but are amendable to appropriate medical therapies. Pain improves with opiate analgesia. If the patient is given heparin, the patient will undergo pulseless electrical activity (PEA) arrest and the case will end at the discretion of the facilitator. Alternatively, facilitators may have a cardiothoracic surgeon call in once the aortic dissection is identified and express their displeasure at heparin and/or antiplatelet medications having been administered.
If learners call an ST-elevation myocardial infarction (STEMI) alert or attempt to call cardiology/the catheterization (cath) lab, learners will be notified that cardiology is in the cath lab currently with another patient and are unable to return their page. If learners contact cardiothoracic surgery and have not given the patient heparin, the surgeon will be amenable to coming down to the emergency department and the case will end. How the scene unfolds: Patient is a 50-year-old female who presents to an academic emergency department with chest pain. The actor/confederate in the nursing role will start the case by first presenting an electrocardiogram (ECG) to the learners, stating "50-year-old female with chest pain came into triage. Here's her ECG. We just brought her back into a bed." If asked, a previous ECG is available. After the first ECG from today is reviewed, any repeat ECGs during this encounter will be unchanged. If the patient is asked specific details about her symptoms, her chest pain is sharp, radiates to her back, began suddenly, and causes her difficulty in breathing. The patient is diaphoretic with discrepant radial pulses to palpation and an aortic regurgitation murmur. If bilateral upper extremity blood pressures are checked, there is a difference greater than 20 mmHg between both arms. Laboratory findings demonstrate an elevated troponin, an elevated d-dimer, and a CXR with a widened mediastinum. If requested, a previous CXR will be shown that shows a normal mediastinum and a previous ECG will be shown that is non-ischemic. Any repeat ECGs after the first ECG will 33 be unchanged. Hypertension and tachycardia will worsen at minute 6 but are amendable to appropriate medical therapies. If the patient is given heparin, the patient will undergo pulseless electrical activity (PEA) arrest and the case will end at the discretion of the facilitators, or, alternatively, cardiothoracic surgery calls in when the aortic dissection is diagnosed to admonish the team for giving the patient heparin and/or antiplatelet therapy.

Equipment or Props
If learners call an ST-elevation myocardial infarction (STEMI) alert or attempt to call cardiology/the catheterization (cath) lab, learners will be notified that cardiology is in the cath lab currently with another patient and are unable to return their page. If learners contact cardiothoracic surgery prior to the patient undergoing PEA arrest, the surgeon will be amenable to coming down to the emergency department and the case will end. Providing a hand-off to cardiothoracic surgery is strongly suggested as a required step prior to ending the case scenario. The length for all of these measures to be achieved should be approximately 15 minutes for a 3-to 4-person team.
Non-ideal management should include anti-platelet or heparin administration, not treating the patient's pain, failure to perform a deliberate physical exam including checking for pulse symmetry and a cardiac murmur, failure to correctly interpret the patient's CXR, failure to administer medications to lower the patient's blood pressure and heart rate in a timely fashion, and delay of contacting cardiothoracic surgery.

Critical actions:
1. Recognition of diastolic murmur 2. Palpate radial pulses simultaneously (or obtain blood pressures in bilateral upper extremities) 3. Correctly interpreting CXR as having a widened mediastinum 4. Ordering beta-blockade to decrease heart rate to a goal of 60 beats per minute 5. Ordering anti-hypertensive therapy to a goal systolic blood pressure of 100-120 mmHg 6. Contacting cardiothoracic surgery for disposition Hypertension and tachycardia will worsen at minute 6.
If learners order IV push medications to decrease heart rate/blood pressure, vital signs will respond as below: 10mg labetalol or 10mg hydralazine push: BP decreases to 170/80 right arm 5mg metoprolol push: heart rate decreases to 90 bpm If learners order titratable medications to decrease heart rate/blood pressure, nursing will ask what their vital sign parameter goals are and vital signs will respond appropriately to stated goal over 1 minute. Learners voice concern for aortic dissection and contact cardiothoracic surgery.
If heparin had been given, patient then goes into PEA arrest (sinus tachycardia at 160 beats per minute) with return of spontaneous circulation occurring per facilitator's discretion.
Alternatively: An angry CT surgeon calls in prior to PEA arrest and admonishes team for administering antiplatelets and/or heparin, but ultimately accepts the patient and takes her to the OR.
If heparin has not been given, cardiothoracic surgery asks what their goal vital sign parameters are and accepts the patient to be taken to the operating room.

Aortic Dissection Presenting as a STEMI
Learning Points: 1. ST segment elevation may be due to multiple different etiologies, some emergent and life-threatening. While diagnosing STEMI in a timely fashion is critical, it should not be a reflexive treatment pathway. 2. Aortic dissection is associated with genetic, family, social, and surgical risk factors. 3. Concerning historical elements include rapid onset of severe pain, sharp or tearing quality, radiating or migrating pain. 4. Exam findings in aortic dissection include pulse deficits or asymmetry, neuro deficits, aortic insufficiency murmur, or shock.

Complications of aortic dissection include ischemic limb, renal or abdominal vascular
injury, stroke, STEMI, and tamponade 6. Due to the rate of delayed or missed diagnosis, a high index of suspicion is required.
In one study: Sixty-four percent describe sharp pain, and 50% describe tearing or ripping pain. 9.4% presented with syncope, which is more common in type A. 1 Beware of those who: • report chest AND abdominal pain (pain that crosses the diaphragm).
• report chest pain and neurologic symptoms.
Exam: know what you are looking for BEFORE you start your exam! (be deliberate) • Check for arm BP differential >20 mmHg (left>right), but know that other patients without dissection may also have this. • Aortic regurgitation (diastolic murmur), neurologic deficits, rales/jugular venous distention/hepatojugular reflex. 2 • May be hypertensive or hypotensive (hypotension increases the diagnostic likelihood 3 and worsens prognosis 4 ).

D-dimer
• do not rely on D-dimer alone to exclude the diagnosis of aortic dissection.
• Low or false-negative D-dimer may be seen in: o Chronicity, time of symptom onset, presence of thrombosed false lumen, intramural hematoma, short length of dissection, young age. 5

ECG:
• Patients can present as inferior STEMIs for two reasons. o The first is a dissection is more likely to occur in the greater curvature and thus more likely to obstruct the right coronary artery = right-sided heart failure symptoms. o Second, dissection into the left main is often fatal. 6

CXR
• widening of the aortic silhouette >8 cm on a posterior-anterior film, pleural effusion left greater than right, right tracheal displacement, apical pleural cap , left paraspinal stripe, aortic kinking. 7 Treatment: • The ideal target blood pressure for acute aortic dissection management is currently undefined by controlled trials and must be tailored to each patient, but an appropriate goal is a systolic pressure of < 120 Hg while maintaining end-organ perfusion o A suggested heart rate goal is 60 beats per minute 8 • Beta-1 selective adrenergic antagonists will decrease inotropy and chronotropy: esmolol, metoprolol • Alpha-1:beta-1 and beta-2 adrenergic antagonist (7:1 alpha to beta ratio): intravenous labetalol • Peripheral vasodilation: nitroprusside.
o beta-1 blockade should be performed before initiating nitroprusside to prevent reflex tachycardia Consequences of aortic dissection • Stroke, tamponade, STEMI, end organ damage to kidneys with distal propagation of dissection • Aneurysmal dilation of the aorta may compress regional structures such as the esophagus, the recurrent laryngeal nerve, or the superior cervical sympathetic ganglion, causing dysphagia, hoarseness, or Horner's syndrome.